Global Burden of Cardiovascular Diseases

In recent years, the dominance of chronic diseases as major contributors to total global mortality has emerged and has been previously described in detail elsewhere. By 2005, the total number of cardiovascular disease (CVD) deaths (mainly coronary heart disease, stroke, and rheumatic heart disease) had increased globally to 17.5 million from 14.4 million in 1990. Of these, 7.6 million were attributed to coronary heart disease and 5.7 million to stroke. More than 80 percent of the deaths occurred in low and middle income countries (WHO, 2009e).

Based on 2007 to 2010 data, 33% of US adults ≥ 20 years of age have hypertension. This represents ~ 78 million US adults with hypertension. The prevalence of hypertension is similar for men and women. African American adults have among the highest prevalence of hypertension (44%) in the world.

Rheumatic aortic regurgitation has become less common than in the preantibiotic era, but nonrheumatic causes are frequent and are the major cause of isolated aortic regurgitation. These include congenitally bicuspid valves, infective endocarditis, and hypertension. Many patients have aortic regurgitation secondary to aortic root diseases such as cystic medial necrosis, Marfan’s syndrome, aortic dissection, ankylosing spondylitis, Reiter’s syndrome, and Syphilis.

Clinical Findings

A. Symptoms and Signs
The clinical presentation is determined by the rapidity with which regurgitation develops. In chronic regurgitation, the only sign for many years may be a soft aortic diastolic murmur. As the valve deformity increases, larger amounts regurgitate, diastolic blood pressure falls, and the left ventricle progressively enlarges. Most patients remain asymptomatic even at this point, and an often prolonged plateau phase, characterized by stable left ventricular dilation, occurs. Left ventricular failure is a late event and may be sudden in onset. Exertional dyspnea and fatigue are the most frequent symptoms, but paroxysmal nocturnal dyspnea and pulmonary edema may also occur. Angina pectoris or atypical chest pain may be present. Associated coronary artery disease and syncope are less common than in aortic stenosis.

Hemodynamically, because of compensatory left ventricular dilation, patients eject a large stroke volume which is adequate to maintain forward cardiac output until late in the course of the disease. Left ventricular diastolic pressure remains normal also but may abruptly rise when heart failure occurs. Abnormal left ventricular systolic function, as manifested by reduced ejection fraction and increasing end-systolic left ventricular volume, is a late sign.

The major physical findings relate to the wide arterial pulse pressure. The pulse has a rapid rise and fall (water-hammer pulse or Corrigan’s pulse), with an elevated systolic and low diastolic pressure, owing to the large stroke volume and rapid diastolic runoff back into the left ventricle, respectively. The large stroke volume is also responsible for characteristic findings such as Quincke’s pulses (subungual capillary pulsations), Duroziez’s sign (diastolic murmur over a partially compressed peripheral artery, commonly the femoral), and Musset’s sign (head bob with each pulse). The apical impulse is prominent, laterally displaced, and usually hyperdynamic and may be sustained. The murmur itself may be quite soft and localized; the aortic diastolic murmur is high-pitched and decrescendo. A mid or late diastolic low-pitched mitral murmur (Austin Flint murmur) may be heard in advanced aortic regurgitation, owing to obstruction of mitral flow produced by partial closure of the mitral valve by the regurgitant jet.

When aortic regurgitation develops acutely (as in aortic dissection or infective endocarditis), left ventricular failure, manifested primarily as pulmonary edema, may develop rapidly, and surgery is urgently required. Patients with acute aortic regurgitation do not have the dilated left ventricle of chronic aortic regurgitation. In the same way, the diastolic murmur is shorter and may be minimal in intensity, and the pulse pressure may not be widened, making clinical diagnosis difficult.

B. Diagnostic Studies
The ECG usually shows moderate to severe left ventricular hypertrophy. Radiographs show cardiomegaly with left ventricular prominence.

Echocardiography can demonstrate whether the lesion involves the aortic root or if valvular disease is present. Serial assessments of left ventricular size and function are critical in determining the timing for valve replacement. Doppler techniques can qualitatively estimate the severity of regurgitation, though it should be noted that “mild” regurgitation is not uncommon and should not be overinterpreted. Scintigraphic studies can quantify left ventricular function and functional reserve during exercise-a useful predictor of prognosis.

Cardiac catheterization can help quantify severity and is used to evaluate the coronary and aortic root anatomy preoperatively.

Treatment & Prognosis

Aortic regurgitation that appears or worsens during or after an episode of infective Endocarditis or aortic dissection may lead to acute severe left ventricular failure or subacute progression over weeks or months. The former usually presents as pulmonary edema; surgical replacement of the valve is indicated even during active infection. These patients may be transiently improved or stabilized by vasodilators.

Endocarditis is an inflammation of the inside lining of the heart chambers and heart valves (endocardium).

Causes, incidence, and risk factors
Endocarditis can involve the heart muscle, heart valves, or lining of the heart. Most people who develop endocarditis have underlying valvular heart disease.

Chronic regurgitation has a long natural history, but the prognosis without surgery becomes poor when symptoms occur. Vasodilators, such as hydralazine, nifedipine, and angiotensin-converting enzyme inhibitors, can reduce the severity of regurgitation, and prophylactic treatment may postpone or avoid surgery in asymptomatic patients with severe regurgitation and dilated left ventricles. Beta-blocker therapy may slow the rate of aortic dilation in Marfan’s syndrome. Surgery is usually indicated once aortic regurgitation causes symptoms. Surgery is also indicated for those with few or no symptoms who present with significant left ventricular dysfunction (ejection fraction < 45- 50%) or who exhibit progressive deterioration of left ventricular function, irrespective of symptoms. Although the operative mortality rate is higher when left ventricular function is severely impaired, valve replacement or repair is still indicated, since left ventricular function often improves somewhat and the long-term prognosis is thereby enhanced.

The operative mortality rate is usually in the 3-5% range. Aortic regurgitation due to aortic root disease requires repair or replacement of the root, a more difficult operation. Following surgery, left ventricular size usually decreases and left ventricular function improves, except where dysfunction has been present chronically.

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